Safety control device for motor vehicles



Jan. 25, 1949.

H. T. HIGGINS SAFETY CONTROL DEVICE FOR, MOTOR VEHICLES Filed Feb. 17, 1945 v S'Sheets-Sheet 1 l A l 2 k 8 as 64 97: 7s 74 INVENTOR.

HAROLD r mam/vs.

ATTORNEYS.

Jan. 1949. HlGGlNs I 2,459,938

SAFETY CONTROL DEVICE FOR MOTOR VEHICLES Filed Feb. 17, 1945 I 5 Sheets-:Sheet 2 1N VEN TOR.

HAROLD TI/IG'GVNS,

ATTORNEYS.

Jan. 25, 1949.- j H HlGGms 2,459,938

SAFETY CONTROL DEVICE FOR MOTOR VEHICLES Filed Feb. 17, 1945 5 Sheets-Sheet 3 Jay 6;

IN V EN TOR.

Jan. 25, 1949. r T, lNs 2,459,938

SAFETY CONTROL DEVICE FOR MOTOR VEHICLES INVENTOR.

meow 77 f/MG/NS.

. IQ. I i V I HTTOR/VE/ SI Jan. 25, 1949. H. T. HIGGINS SAFETY CONTROL DEVICE FOR MQTOR VEHICLES 5 Sheets-Sheet 5 Filed Feb. 17, 1945 MEN mm M m m an .3 W g. E n J HAROL D 7. Hi6 GIN-S.

a N ooooo AT ORNEYS.

Patented Jan. 25 1 949 U N-ITED S TIA-T ES PAT ENT OFF I CE SAFETY CONTROLYVDEVVICE' FOR MOTOR VEHICLES llaroldT, Higgins, Boston, Mass. Application "February '17, 1945, Serial No.- 57.8;532'

1 6 Claims.

1 My present invention relates to a control device for usein so connecting a pair ofmembers in the means by which-the throttle valve of an' engine is actuated that normal acceleration-is possible only whena predetermined pressure exists at the source of brake operated power devel oped and maintained by the compressor driven by the engine.

Consideration'of'a number of accidents involving vehicles, particularly busses, equipped with power'operated brakes leads me to the conclusion that, in many'instances, the cause of the accidents was the fact that the vehicle was operated at a time when thepressure at the source was below a minimum safe-brake operating pressure; The lack of adequate brake operating'pressure may sometimes be attributed-totheuseof the vehicle before the compressor had'builtup the pressure at the source .to .a safe level. Sometimes the lack of a safe operating pressureis due to leaks or breaks inthe pressure lines.

While most pressure .brakesystems have a pressure indicator, such in no way controls the operation of the vehicle and the operator, through carelessness, or because of other-duties; may fail to notice the indicator at crucial timesor he may ignore the fact that the indicator shows that it is unsafe to operate the vehicle;

Inxaccordancewith my. invention, I provide a device comprising a unit connecting a pairof throttle valve actuatingmembers' and pressure operable means by which the connecting unit is rendered operative in response to a predetermined minimum pressure'at the source ofbrake operating pressure and is rendered inoperativeto thereby prevent normal accelerationwhenthepressure-at thesource drops below-that predetermined minimum; When the device is operative, the pair of members are interconnected as -a unit but when it is inoperative, the members-have limited movement relative to each other to'decrease the extent' to which thethrottle valve maybe opened as theaccelerator pedal is depressedby the operator.

In addition to this control of the throttle valve, which by itself immediately renders-impossible normal operation'of the throttle valve unless a'dequatebrake operating pressure is available, my

invention may also provide controls :for 'theen'- gine-circuits. By these controls, such circuits are' opened when only an inadequate pressu're isavailable to operatethe brakes. These circuits can:- notbe closed until adequate brake operating pres sures are available except when i certain safety precautions are observed. For example, the engine may be started and run, when-the parking brake is applied, atsufiicient R. P. M. to develop adequate brake operating pressure at the source orto permit-the movement, in emergencies, of

' the vehicle at aslow rate of speed to a safe place.

My invention is capable of various embodiments making itadaptable .to various brake operatin systemsand to provide a-wide range of safe controls-for thevehicle. In the accompanying drawings; I have shown several characteristic embodiments of my invention from which its ,manynovel features-andadvantages will be readily apparent.

In* the drawings:

Fig. l is aschematic'view showing a bus chassis,

its pressure operated brake system and the .rela-' tionof my invention to that system and to the throttle-valve actuating means.

Fig. 2--is'a partlysectioned view of a device com.- bining a valveoperableat a predetermined pressure and apressure operated connecting unit for the throttle actuating members.

Fig. 3-sh'ows, in" a'longitudinal section, a modification of'the device shownin Fig. 2.

Fig. 4 is a longitudinalzsection of a connecting unitinaccordance'with my invention for connecting'a pair'of throttle valve'actuating memadapted for use when the pair of members to be connected-are a'shaft-and a shaft rotating arm actuated by the accelerator pedal.

Fig. 8 'shows; in elevation, the spring controlled arm -fast-on the shaft, the arm actuated .by theaccelerator'ipedalrand'the means by which thearms ar'e interconnected after predetermined partial rotation of the accelerator actuated arm relative to the shaft when an inadequate brake operating pressure :exists at the source.

Fig. 9 is a fragmentary and partiy sectioned end view of the connecting unit of 7 when inoperatively positioned by the power operated means.

Fig. 10 shows;'in a'similar view, the connecting unit of Fig. 7 when operatively positionedby thepower operated means.-

Fig. 11 is a section along the lines ll-ll of Fig. '7.

Fig. 12 shows one of the arms in elevation.

Fig. 13 is a fragmentary sectioned view of the unit of Fig. 7.

Fig. 14 is a fragmentary, partly sectioned View of a modification of the power operated means of the device of Fig. 7.

Fig. 15 is a schematic view showing'a typical installation in accordance with my invention utilizing the device of Fig. 7, and

Fig, 16 is a fragmentary view indicating the use of a device of the type shown in Figs. 2-,-5 in j the installation of Fig. 15.

Introduction My invention may be most conveniently introduced by reference to Fig. 1 in which I haveshown the chassis 23 of a bus or other vehicle having an engine 2! having a throttle valve con- 20 trolled carburetor indicated at 22, an accelerator pedal 23 and linkage or equivalent means 24 to be actuated by the accelerator pedal 23 to vary I the position of the throttle valve. 7

In motor vehicles having an air or like power 25 or pressure operated brake system, the engine 2! conventionally operates means such as a compressor, which delivers air under pressure through the supply line 2Z5 to build up and maintain the fluid under a desired pressure in the tank 23 which is the source of air or fluid under pressure. At 21, I have indicated a brake pedal effective, when actuated, to cause a flow of air under pressure through the pressure line 28 from the tank 23 through the supply lines 23 to the 5 Wheel brakes, indicated generally at 33.

The effectiveness of the braking system de pends, of course, on the availability of adequate pressure and my invention is concerned with means for automaticallymaking normal opera- 0 tion of the vehicle impossible except when an adequate brake operating pressure is available. 7 I accomplish this result by utilizing pressure operable means such as the device indicated generally at 3! only in Fig.1 to connect a pair of 115 members anywhere in the actuating means controlled by the accelerator pedal to vary the position of the throttle valve. In Fig. 1, I have shown for convenience the device 31 as connecting the members 32 and 33 of the linkage 2G. The device 50 31 is connected to the source 25 by the pressure line 33 by means responsive to the pressure at the source whenthe pressure therein is at a predetermined minimum and is rendered effective by such pressure to connect the members 32 and 33 as 55 a unit. Should the'pressure in the tank 26 be below that predetermined minimum, the device 3! permits relative movement between the members 32 and 33 thereby to render normal acceleration impossible. For reasons that will subse 6O quently be apparent; such relative movement, when the device 3| is inoperative, limits the extent to which the throttle valve can be opened by the actuation of the accelerator pedal 23.

Devices in accordance with my invention accordingly consist of pressure operable means such as a connecting unit rendered operable by air under pressure and means, responsive to a. predetermined pressure, to render operable the connecting unit.

The actuation of the connecting unit also may be employed to actuate a switch in control of electric circuits, shown in Fig. 15, and discussed in connection therewith to further control the operation of the vehicle or its engine.

The device of Figs. 2-6

In Figs. 2-6, I have shown embodiments of my invention for use in connecting the members 32 receiveadjusting nuts 4i and 42 establishing respectively a stop for the head 39 and lock nuts for the head 43 through which the supports are threaded. A pressure responsive element such :as the bellows unit 43 is attached to the heads 39 and ll? and to the head 33 I attach one end of therod 33 of the throttle valve positioning linkage 24. I

The, head -.has a cylinder 44, the head 45 of which is supported by the rods 31 and at 46 I have shown an inlet port into which the end of the pressureline 34 of- Fig. 1 is threaded. The cylinder head. supports a bellows unit 48 which has an axial passage 49. H

I form the headfifl with a port 56 tapered as at 5| to establish a seat for the tapered head 52 of the valve pin 53 which extends through the axial passage 49 of the bellows unit'48 with its flange 54 attached to the end thereof. At 55 I have shown a return spring urging the valve 52 into its unseated position. The spring 55 seats in guide cups 56 and is adjustably tensioned by the nut 5'! backed by a lock nut 53. For the sake of clarity, I have omitted the nut receiving threads on the valve pin 53.

The valve pin 53 has an axial bore to receive themember 59 which'has'at one end a head 59 normally blocking the bore under the influence of the springfil attached to the, head 36. The other end of the member 59 is disposed to engage with the seat 62 in the bellows unit 43to effect the disengagement of the head 68 from the flange 53 when the valve head 52 engages the seat 5! to close the port 50; I g

" By this construction, I provide adevice that permits predetermined relative movement be-- tween the members 32 and 33 when the pressure at the source 26'is below a predetermined minimum. This results from the fact that the bellows unit 43 collapses unless its interior is subjected to a predetermined pressure.

' Pressure within the cylinder 44 is the same as the pressure within the tank 26. When the pressure Within the cylinder 44 reaches a predeterminedminimum adequate for safe brake operation, the bellows unit 48 collapses and causes the valve pin 53 to move into a position in which its tapered head 52 closes the port 50 and the member 53 engages with the seat 62 to causejits head 53 to disengagefrom the. flange 54 against the action of the spring 5|. -Airunder pressure is, accordingly," admittedto the bellows. unit 43 to prevent its collapse as the accelerator pedal is depressed so'that the members 32 and 33 are connectedas aunit. 7

Shouldthe pressure in the tank 26 drop, for any reason below the predetermined minimum, the bellows unit 48, because of its resiliency and because of the return spring 55, returns to its normal position unseatingthe head 52 to open the port 50 therebyto relieve the pressure in the bellows unit 43. At the same time, themember 59 is carried into a-position in which its head 1 is-- tightly seated against the flange- 54 by the spring 6|. 7 A

' Thedevice 63 of Fig. 3 follows the device of Fig. 2 in that it combines a pressure'operable connection and pressure operable means to render the connection operative. The device 63 comprises a casing 64 into one end of which is adjustably threaded an end wall Gite which the member 32 is connected. The other end wall 66 slidably supports the member 33 which has a piston 51. The casing 64 has a partition 68 establishing a cylinder 69 for the piston 51 and a chamber iii. The cylinder 69 and the chamber 75 are interconnected by a port H having'radially disposed relief passages 72; Atlt; I have indicated a fitting for the pressure line 35 so that pressure in the tank 25 is transmitted to the chamber 76. g v

Fastened at one end to the wall is a bellows unitl l closed at its otherend by a plug 15 having 'asealed passage 16 through which the bellows unit is was initially inflated to the desired pressure. The plug it has a tapered valve portion Tl to seat normally in the port H to close the cylinder 69 iromthe chamber '10. The extremity T3 of the plug 75 is of the same diameter as the port H (in the drawings, working clearances are exaggerated) and between the extremity i8 and the tapered portion H, the plug 15 is of reduced diameter and has ports '59 communicating with an axial bore extending through the extremity l8.

By this construction; when the pressure in the tankZfi reaches a predetermined minimum, the resistance of the bellows unit M is overcome unseating the valve portion 7? so that the extremity '58 blocks the relief ports E2. When the plug i5 is thus positioned, air under pressure flows from thechamberlll through the ports 19 and 89 into the cylinder $3.! against the piston 67 to carry the piston out of contact with the limiting ring 81 against the end wall 68 to extend the member 33 relative to the member 32 and connect them as a unit to render the connection operable to provide normal acceleration.

The endwall 66 has relief ports 82 and the casingtl, adjacentone of the relief ports 82,

relief ports for actuation by the piston 61 as it seats against the end wall 56. The switch 83 is employed to provide an automatic control of the ignition circuits of the engine and has the same function as the switch I52 of Fig. 15 or the switch 940i Fig. 16.

When the pressure at the source is not adequate for safe brake operation, the bellows unit it causes the valve portion 1'! toseat blocking the cylinder 69 from the chamber in and venting the cylinder 68 through the ports 89, re, and F2.

The device of Fig. 3 is particularly well adapted foruse in buses or like vehicles because of its simplicity of construction and because of its reliability. In addition, it should be noted thatthe only possibility of failure is the possibility that the bellows unit it might develop a leak. As this would result in a balancing of pressures, the bellows unit 74 would not move and accordingly the device would remain inoperative and thereby prevent normal acceleration until the unit it was repaired or replacedregardless of available brake operating pressure. Such failure of the device on the safe side is a desirable characteristic of my invention.

In Fig. 4, I have shown a connecting unit*8'5- operation of the unit 85 of Fig. 4.

for use with a pressure operable valve, such, for

exampla'as the valve 86 of Fig. 6. The unit 85' 32 and 33 are located exerts a pull when the accelerator pedal 23 is depressed by the vehicle operator. The position shown in Fig. 4 is the inoperative position in which the member 32 has moved relative to the member 33 substantially far as possible and in such movement, the position of the throttle valve has not been varied. Further movement of the accelerator pedal will cause movement of the throttle valve, but because of the relative movement between the members 32 and 33, only-a limited opening of the throttle valve is possible when inadequate brake operating pressures are available.

When the pressure at the source 26 is at or above a predetermined minimum, pressure is admitted into the cylinder 81 and it moves the piston head 9t against the end wall 85 of the cylinder 8? thereby to connect the members 32 and 33 so that they move as a unit to make posgaged by the dog 96 fast on the member 32 thereby to close the switch at when the members 32 and 33 are connected as a unit.-

The connecting unit 9? of Fig. 5 is, in general, similar to the connecting unit 85 of Fig. 4, but is adapted for use when that part of the linkage 2d in which the members 32 and 33 are located exerts a thrust or push when the accelerator pedal 23 is depressed. t includes the cylinder 87 having a port 9! to receive the conduit i is from the valve 35 when the pressure at the source is'at or above a predetermined minimum. Adjacent the port 92, the cylinder has the stop ring 92. The member 32 is fastened to the end 88* of the cylinder 8? while the member 33 is slidably supported by the end 58 and carries a piston head within the cylinder 8? for movement between a position engaging the end 38 and a position engaging the stop ring 92. At 53 I have indicated a relief port through the wall 8S through which extends the operating button 38 of a normally open switch 99 having the same function as the switch at of Fig. i.

The operation of the unit 9? is similar to the When the pressure at the source 25 is adequate to ensure the safe operation of the brakes, the valve cs admits air under that pressure into the;cylinder 8? thereby to seat the piston 553* against the end 88 simultaneously to extend the members 32 and 33 to make normal acceleration possible,

and to effect the closing of the switch as. When an inadequate brake operating pressure exists in the tank 26, the valve 86 connects the cylinder fi'i'to relief and if the accelerator pedal 23 is then depressed, relative movement between the members .32 and .33 results, decreasing the extent to which the throttle valve can be opened by; depressing the" accelerator 1 pedal 23 and permittingtl'ie switch 99'toop'en';

The valve 86 of Fig. 6 is particularly well adapted for use with the control units 85 and 31. The valve 05 has a mercury well I supported by a bracket IOI. Within the well I00, there is a float I52 having a stem I03 extending through the well cover I34 upwardly into a cylinder I05 where the stem is provided with a piston head I06. The cylinder I05 isshown as supported by brackets 07. Air under pressure is supplied to the cylinder I05 by a pressure line I08 connected to the tank 25 so that the pressure in the tank 23 is opposed by the float I02 and when that pressure reaches a predeterdelivered to or from the port III in the cylinder Bl of the unit 55 or 9?.

The stem I33 has a transverse bore II5 shown as connecting'the chamber II3 to the relief port H2 but adapted to connect the port III to the chamber H3 when the predetermined pres sure on the piston I06 overcomes the resistance of the float I02.

The device of Figs. 7-14 The embodiment of my invention shown in Fig. 7 is utilized to connect the members Ill and I I8 of the throttle valve actuating means 24.

The member III, as shown in fig. 7, is the shaft for the indicated throttle valve II9 and fast on the shaft is an arm I20 controlled conventionally by the spring I 2I urging the valve H9 into its closed position. The member II 8 constitutes an arm loosely mounted on the shaft Ill. The arms H8 and I20 have hub portions I22 and I23 respectively (see Figs. 8 11, and 12) each of which has a radially disposed slot I24 (see Figs. 9, 11, and 12). The hub I22 is cut away to establish a pair of spaced shoulders I25 and I25 engageable by a pin I2? carried by the hub portion I2 3 (see Fig. 8) so that predetermined partial rotation of the arm H8 is independent of the shaft II'I' until the pin I21 is engaged by the shoulder I25. By this construction, I provide a connection restricting the extent to which the throttle valve II 9 may be opened by the accelerator pedal 23 and I provide means operated by the accelerator pedal or like control to connect the arm II8 to the shaft II as a unit when the fluid pressure at the source is at or above a predetermined minimum.

As illustrative of such means, I form a sleeve I28 with a bore I29 of the diameter of the hubs I22 and I23 laterally extended to permit the sleeve I23 to be shifted transversely relative to their axis. The sleeve I28 has rib portions I33 and I3I. in the slot I24 of the hub I23 to cause the sleeve I28 to rotate with the shaft III. The rib portion I 36 is disengaged from the slot I24 of the hub I22 when the sleeve I23 is in the position shown in ,Fig. 9 thereby to permit the arrn H8 to turn relative to the shaft III. When the sleeve is in the position shown in Fig. 10, the rib portion I30 enters'the slot I 24 of the hub I22 The rib portion I3I always remains.

' interconnect the thereby connecting the arm H8 and the shaft III as a unit.

In accordance with my invention, I employ a sleeve I32 within which the sleeve I28 is free to rotate. Into the sleeve, I32 1 thread a rod I33 on a hub I34 threaded into a carrying houslng I35. 7

At I35 I have indicated a power operable unit to move the housing I35 and the sleeve I32 as a unit to render the connecting unit operable or inoperable to permit or prevent normal acceleration. The unit I35 consits of a casing I31 having a chamber I38 having an adjustable end wall I39 andan axial port I40, vented by radial relief passages I4I. V

A fitting I43 for the pressure line 34 establishes a port through which airunder pressure is admitted into thechamber I38. A bellows unit I44 supported at one end by the wall I39 is closed at its other end by'a plug I55 having, a sealed passage I46 by which the bellows unit I44 was initially inflated to a desired pressure. The plug 235 tapers at I5? to normally close the port I40 under the influence of the bellows unit I44.

i'he extremity I48 of the plug I45 is cylindrical and is dimensioned to fit theport I40 so that when the pressure in the tank 26 and accordingly the pressure in the chamber I30 reaches a predetermined minimum, and the resistance of the belioWs unit M4 is overcome to unseat the tapered port I4? thereby to open the port I40, the relief ports i4i are blocked by the cylindrical portions I48. The cylinder I3? has a hub I43 (see Fig. 13) having an axial passage to slidably receive the rod I 53 threaded at one end'into the plug extremity I38 and at its other end into the support i5I for the normally open switch I 52. The support IiiI carries the housing I35. By this construction, as the plug I 45 is unseated by the collapse of the bellows unit I44,.the housing I35 is moved therewith exerting a pull on the sleeve I32 through the rod I33.

'hub M9. The pin I56 traverses the bore in such relation to the switch closing stem I54 that as the'housing I35 is moved to cause the members II'I, H8, and I20 to be interconnected as a unit to permit normal acceleration, the stem I54 engages the pin I56 and causes the switch I52 to close.

In Fig. 14, I have indicated a power operable unit I5? adapted for use in place of the unit I35 of Fig. '7. The unit I51 comprises a casing I 58 having a threaded port I59 to receive the end of the pressure line 34 to deliver air under tank pressure into the chamber I86. One end of a bellows unit I6I is fastened to the casing I58 and has an axial passage for the rod I50 to which the other end of the bellows unit is secured. The rod I50 is slidable in the casing I58. At I83, I have shown a bellows unit fastened at one end to the, casing I53 and at its other end to the shaft I50 The unit I55 is initially inflated to a predetermined value and sealed as at H33. The bellows unit I5I serves as a shaft seal and is of relatively small size. It will be apparent that when a predetermined pressure exists in the chamber I55 the bellows unit I66 collapses mov ing the rod I53 through a sufficient stroke to .embers III, IE8, and I20 as a unit. 3

"Theinstalldtion o'f'Fzgs. 1'5 and 16 .InFig. 15,.I have'indicated schematically a wiring diagram of aninstallationin accordance with my invention. .5

At I61 and I68, I have indicated a battery and generator respectively as the. conventional source of electrical energy of a .motor vehicle. The lead I69 includes the ignition. switch I adjacent the dash board I'll. .At I12 Ihave indicated a horn 10 as illustrative of conventional warningsignals andat I13 I have suggested the ignition coil as representative of the engine..circuits.

At'I'I4 I have indicated a circuit from the .ignitionswitch I10 havingparallel switches H5 and I15. In the position shown in'the drawings, the switch I15 connects the circuit I14 to the horn I12 and the switch'l16. connects the circuit I14 to the lead I11, the contact I18 of which is engageable bya switch I19 to close the circuit I14 20 to the ignitioncoil'I13. The switch I19 is shown as normally engaginga contact I89 in a lead I8I to the contact I82.

In order tomake it possible to startthe en gine without sounding the horn I12, I control the switches I15 and I1Ii-bya relay I83 energized' by the circuit I84 when the parking brake I85 is applied to close the normallyopen switch I86 .and the ignitionswitch I10 is turned on. When the relay I83 isthus energized, the switch. I15 is positioned to disconnect the horn I12 'from the circuit I14 and to engage the contact I81 connected by the lead'l88 to the switch I89.

Before the ignition coil I13 can be energized .topermit the engine to be started, it is necessary to position the switch I19 to engage the contact I18. To accomplish this,.I-employ.a relay I99 which may be energized by manually holding thepush button switch .I9I in a position to connect the circuit I92 to the lead I69 and thereby 40 position the switch I19 to complete the circuit to the ignitioncoil. Thecircuit I95 then includes the switch. I96 in its shown position, the lead I11 to the contact I18 and the switch I19.

When the. relay I90 is energized, it also closes the switch I93 connectedbythe lead I94 to the switch I89.so that the circuit I14 becomes a holding circuit maintaining the relay I98 energizedon therelease of the push button switch I9I solong as the relay I99 is .de-energized and the relay I83 is energized. The holding circuit consists of the circuit-I14, the switch I15, the lead I88, the switch I89, the lead I94, and the switch I93.

In its released position, the push button switch .I9I connects the power lead I95 to the lead-I69 and to the lead I11 when the switch I98 is closed in the position shown which is its normal position when the re1ay I99 is deenergized.

As the circuit tothe ignition coil I13 is complete whentherelays' I83 and I90 are energized,

. the engine may bestarted.

At I91, 'I' have indicatedgenerally a clevicein accordancewith my invention of thetype shown in Fig. 7. This hasits switch I52 in control of 5 eration of the brakes, themembers I I1, H8, and 70 I29 are not interconnected .until after predetermined partial rotation of the member "I I8 relative to themember II1 so that the extent to which the throttle valve maybe opened by actuation .of the: accelerator pedal,- isv greatly .reduced.

vto the pilot light 299.

10 Adequate'acceleration of the engine is possible for warming it up and for building up a desired air pressure in the tank26, but such acceleration permits the vehicle to be driven at only a slow speed. Furthermore, under the conditions being discussed, the parking brake I is applied.

When such air pressure is available, the device I91 is operative 'to connect the members 1, IIO,and I20 to make normal acceleration possible and simultaneously the switch I52 is-closed so that the relay I99 is energized. The operator may then release the brake I85. Should he release the brake I BE-prematurely, the relay I89 would be deenergized breaking the holding circuit for the relay I99 and completing the circuit to the horn I12 and at the same time opening the circuit to the ignition coil I13.

When the relay I99 is energized, the switch I89 engages the contact I82 of the lead It! thereby also opening the holding circuit tothe relay I90. At the same time, the relay I99 positions the switch I95 to engage the contact -29I maintaining the relay l83 energized. The circuitto the ignition coil 113 then comprises the power -line-l14, the switch I15, the lead I 88, the switch I99, theleadIBI .to the contact I80, and the switch I19.

Should the pressure in the tank 26 drop below the predetermined minimum, the switch I52 opens breaking the circuitto the relay I99 and As a result,-the holding circuit for the relay I93 is opened and the circuit to the ignition coil is also opened so that :the compression of the engine has a braking effect on the vehicle. As the relay I83 is no longer energized, the circuit I14 is also complete to the horn I12-through the switch I15 and the horn accordingly sounds. I have shown asafety switch 202 in the circuitI98 to-permit this control of the motor vehicle. Such safety switches may be located-any place in the vehicle-desired to provide maximum safety and are normally openswitches held closed under glass asat 299 or by. emergency door latches.

Should the pressure in the tank 29 fail at a time when or under circumstances that makes it necessary to move the vehicle Without waiting for adequate brake operating pressure to be built up or a brokenline, for example, to berepaired, .this may be done.

t will be noted that one of the functions of the relay I83-is to enable the horn. I12 to be disconnected from the circuit I14 and to establish a holding circuit forrthe relay I99. The circuit I84 controls the relay I89 directlyand the circuit I98 controls the relay I99 which, when energized, establishes the holding circuit for the relay I83 when the switch I99 engages the contact 29I. By manually holding the switch I9I toclose the circuit I92 to the relay I99, therelay I90 may be heldclosed to position the switch I19 to.include the ignition-coil I13 in the circuit I14 with the horn I12. 'The circuit I14 then includes the switch I99, the lead I11 to the contact I18 and the switch I19. As the device I91 is inoperative-to establish a normal range of acceleration, the vehicle may-only be driven at a slow speed. Should an attempt be made to hold the switch I9I closed when adequate brake operating pressure exists at the source 25, the circuit to the relayI99 is closed,

but the circuit I95 is open. As the circuit I95 supplies the energy for the holding circuit from the relayI83, theignitioncircuit is interrupted after which the horn circuit is energized.

.In Fig. -16,.I have indicated a deviceuof the Conclusion From the foregoing, it will be noted that my invention makes possible the safe control of motor vehicles equipped with brakes operated by air under pressure. As will be apparent from the modification of my invention shown in the drawings. I have minimized the use of springs and the like which might tend to break or become so fatigued in use as to interfere with reliability in operation. It will also be apparent that I have made it difficult to tamper with the device and have provided that any failures of the device to operate will be in the direction of safety.

What I therefore claim and desire to secure by Letters Patent is: c

1. A control device for use in a vehicle having a pressure operated brake system including a source of fluid under pressure, a throttlevalve controlled engine driving means developing and maintaining fluid under pressure at said source,

and accelerator pedal actuated means to control said throttle valve and having a pair of members to be connected, said control device comprising pressure operable means normallyinterconnecting said pair of membersto provide relative movement therebetween to limit the extent to'which said throttle valve can be opened by said pedal, said means being operable to connect'said pair of members to increase the extent to which the throttle valve can be opened by actuating said pedal, and means responsive to a predetermined.

pressure at said source to deliver fluid under pressure to said pressure operable means to render it operable.

2. The control device of claim 1 and a control circuit includin a normally open switch c osed when the pressure operable means are rendered operable.

3. The control device of claim 1 in which the means responsive to a predetermined pressure at the source comprise a cylinder, a mercury well, a float in the well, a piston in the cylinder, a valve body, a stem interconnecting thefioat and the piston and slidab e in the body, means to deliver fluid from the source to the cylinder, the valve bodyhaving first and second ports, one of the ports constituting a relief port, and means conmeetin the other of the ports to the source, and a third port connected to the pressure operable means, and the stem has a passage normally interconnecting the relief and third ports but operative to interconnect the second and third ports when the fluid pressure against the piston moves the stem a ainst the influence of. the float.

4. In a vehicle-having an engine controlled by a throttle valve and a brake operating system having a source of power developed and maintained by means driven by the engine, a first member connected to said throttle valve, a second member to be actuated by the operator of the vehicle, and pressure operated means responsive to predetermined pressure at said source to connect said members as a unit, said means having an inoperative position in which movement of said second member is relative to said first member.

5. A unit to connect a pair of members of the acce erator pedal actuated means in control of the throttle valve of a vehicle engine, said unit comprising a cylinder'connected to one of said members, a pressure responsive element connected to the other of said members and mounted .12 within said-cylinder for movement between a first position in which only a predetermined partial movement of the throttle valve results from the actuation of said pedal and a second position in which the extent to which said throttle valve may be opened by actuation of said pedal is increased, said cylinder having a port through which element operating fluid under pressure is admitted to operate said pressure responsive element and to carry it into said second position.

6. The unit'of claim 5 in which a normally open switch is closed by the operation of the pressure responsive element. I 7. A control device for use in a vehicle having a pressure operated brake system including a source of fluid under pressure, a throttle valve controlled engine driving means developing and maintaining fluid under pressure at said source, and accelerator pedal actuated means to control said throttle valve and having a pair of members to be connected, saidicontrol device comprising a connection between said members movable between a first position in which relative movement between said members is permitted thereby to limit the extent to which said throttle valve can be opened by said pedal, and a second position in which said members are interconnected as a unit,

pressure operable means in control of said connection normally maintaining said connection in its first position, and means responsive to a predetermined pressure at said source to deliver fluid under pressure to said pressure operable means to actuate it to establish said second position of said connection.

8. A control device for use in a vehicle having a pressure operated brake system including a source of fluid under pressure, a throttle valve controlled engine driving means developing and maintaining fluid under pressure at said source, and accelerator pedal actuated meansto be connected to the shaft of said valve, said device comprising a connecting unit comprisingan arm connected to said means and mounted'on said shaft for rotation independently thereof, and means to connect said arm to said shaft, said means having a first position normally limiting the extent to which said arm rotates relative to said shaft and a second position in which said arm and said shaft are connected as a unit, and pressure operable means connecting said unit and being normally operative to maintain said connecting means in said first position, said pressure operable means being responsive to a predetermined pressure at said source to effect said second position of said connecting means. I

9. The control device of claim 8 in which the pressure operable means includes a casing, a member movable relative theretounder theinfluence of the predetermined pressure and a normally open switch carried by the member to be closed. on relative movement of the member.

10. The control device of claim 8 in which the pressure operable means comprises a casing having a chamber and a port to admit fluid under pressure from the source and a hub, a bellows unit mounted in the chamber, a rod carried by said unit and slida'bly supported in the casing, and a second bellows unit sealed to the hub and to the shaft and being of smaller size than the first named bellows unit.

11. The control device of claim 8 in which the pressure operable means comprises a casing having a chamber, a port to admit fluid under pressure from the source to the chamber; an axial port, and relief ports connected 'tothe axial port,

axial port to seal the first chamber, and a second valve portion blocking the relief port-s when the axial port is unblocked.

12. A control device for use in a vehicle having a pressure operated brake system including a source of fluid under pressure, a throttle valve controlled engine driving means developing and maintaining fluid under pressure at said sou "cc and accelerator pedal actuated means to control said throttle valve to be connected to the throttle valve shaft, said shaft and said device comprising a unit comprising a spring controlled arm fast on said shaft, an arm connected to said means and mounted on said shaft for rotation independently thereof, both of said arms having slotted hubs, a projection carried by one of said hubs, the other of said hubs having a pair of spaced shoulders to receivesaid projections between them and to be engaged thereby to limit the independent rotation of said second arm relative to said shaft, a sleeve having a bore to receive said hubs, said bore being transversely extended to permit said sleeve to be shifted transversely relative to the axis of the shaft between first and second positions and having a pair of slot entering projections, one of said projections remaining entrant of the slot in the hub of said first arm in said first or second positions and the other of said projections being entrant of the slot in the hub of said second arm only said sleeve is in said second position, a second sleeve rotatably receiving said first sleeve, and power operated means responsive to the pressure at said source and connected to said second sleeve to move said first sleeve into said second position to connect said second arm and said shaft as a unit.

13. A control device for use in a vehicle having a pressure operated brake system including a source of fluid under pressure, a throttle valve controlled engine driving means developing and maintaining fluid under pressure at the source,

and accelerator pedal actuated means to be connected tothe valve to control its position and having a pair of members, said device comprising a connecting unit connecting said pair of members, said unit having a first position in which predetermined relative movement between said members results on the actuation of said pedal and a second position in which said members are connected as a unit, and pressure operable means, said pressure operable means comprising a casing, a pressure responsive element in said casing, a member connected to said element and slidably supported by said casing, said member having an axial bore and a slot transversely interconnecting said bore, a pin carried by said casing to extend through said slot, a housing connected to said member and to said unit, and a normally open switch in said housing, said switch including an operating stem extending into said bore to engage with said pin. to close said switch when a predetermined pressure actuates said element to move said member relative to said casing.

14. A control system for motor vehicle having fluid pressure operated brakes and a source for fluid under pressure, a parking brake, a throttle valve controlled engine driving means developing and maintaining fluid under pressure in said source and having an ignition circuit and elec- "is trically operated signalling means operator actuated means connected to the throttle valve and having a first position in which only a predetermined partial opening of said 'valve can be effected by the operator and a second position in which the extent to which the throttle valve may be opened-by the operator is increased, said system comprising first, second and third relays, first and second switch means operated by each of said relays, a circuit to each of said relays, first and second power circuits, first and second holding circuits, first and second leads to connect the power circuit to the ignition circuit, and a lead to the signalling means, said first holding circuit including said first relay, first switch means of said first relay, second switch means of said second relay and second switch means of said third relay to connect said first holding circuit to said first power circuit when said first and second relays are energized and said third relay is die-energized, said second holding circuit including said second relay and first switch means of said third relay to connect said second holding circuit to said second power circuit when said third relay is energized, said first connecting lead including the second switch means of said first relay, said second switch means of said second relay and said second switch means of said third relay when said second and third relays are energized, and said first relay is de-energized thereby to connect'said first lead to said first power circuit, a third lead in parallel with said switch means of said first lead including said first switch means of said second relay and said second switch means of said first relay when said second relay is de-energized and said first relay is energized, said second lead includes said first switch means of said third relay and said second switch means of said first relay when said third relay is de-energized and said first relay is energized, said lead to the signalling means being closed by said second switch means of said second relay when de-energized, a normally open switch in said circuit to said second relay closed by said parking brake when applied, a, switch normally closing said second power line but operable manually to open said power line and to close said circuit to said first relay, and a normally open switch in said third relay circuit and means responsive to the pressure at said source to close said switch and to establish said second position of said operator actuated means.

15. The control system of claim 14 in which the circuit to the third relay includes at least one normally open switch, and releasable means normally holding the switch closed.

16. The device of claim 1 in which the means responsive to a predetermined pressure at the source comprise a cylinder, a piston in the cylinder, a valve body, a stem connected to the piston and slidable in the body, means to deliver air from the source to the cylinder, the valve body having first and second ports, one of the ports constituting a relief port, means connecting the other of the ports to the source, and a third port connected to the pressure operable means, said stem having a passage normally connecting the relief and. third ports, and yieldable means supporting the stem and operative to permit its movement to interconnect the second and third ports when the fiuid pressure against the piston moves the stem against its yielding action.

- HAROLD T. HIGGINS.

(References on foilowing page) REFERENCES CITED The following references are of 'record in the file of this patent:

' UNITED STATES PATENTS Number I Name Date Hull Mar. 15, 1927 Number 

